It is common practice for recessed fluorescent lamp fixtures, particularly those which employ deep parabolic-shaped louvers, to have the louver assembly fastened to the body of the luminaire by a combination of hinges, latches, and/or springs. In this regard see, for example, U.S. Pat. No. 4,238,815 (Price). Reference may also be made to U.S. Pat. Nos. 4,171,535 (Westermann) and 4,363,082 (Rollins) which illustrate other presently existing luminaires. These additional components and the associated time necessary to assembly same add appreciably to the complexity of the lighting fixture and also to the cost thereof. It is also usual, under present practice, to limit the height of the parabolic louver, particularly the sides and cross pieces (or fins) which interconnect the sides, to the space below the fluorescent lamp. Accordingly, the sides typically do not extend above the lamp level in order to avoid interference between the louver and the lamp when the louver is swung open for servicing (or during installation). This height limitation, however, results in low fixture efficiency due to the corresponding reduction in total louver light control surface area.
At the present time, attempts to provide improved fixture efficiency have included extending louver light control surfaces upwardly by means of separate strips of louver material blanked and formed to follow the louver contour. These strips are attached to the fixture housing to function essentially as a louver extension. However, this solution is costly and does not provide the best results due to differences in curvature between the basic louver and the extension, misalignment between these members, and other problems inherent in this type of construction. Another attempt to improve efficiency involves extending non-removable, longer sides of the louvers upwardly beyond the lamp, but unfortunately this necessitates the elimination of the aforementioned cross pieces in order to permit lamp servicing. In addition, the undesirable lamp brightness is increased primarily because of the absence of such cross pieces.